Implantable cardiac stimulation devices, such as pacemakers and implantable cardioverter-defibrillators (ICDs), typically include a pulse generator that includes circuitry for detecting cardiac arrhythmias and automatically generating and delivering therapeutic electrical stimulations to the patient's heart via one or more indwelling leads. The leads include one or more electrodes that are positioned and secured adjacent to excitable heart cells and an insulated electrical conductor that allows stimulation pulses from the pulse generator to be passed to the electrode(s) and thus to the heart tissue.
The implantation procedure for implantable cardiac stimulation devices involves placement of one or more of the leads in an operating room (O.R.) or electrophysiology (EP) catheter lab. In particular, the lead(s) are positioned and secured in contact with the patient's heart both to sense cardiac activity for detection of possible arrhythmic conditions indicating therapeutic stimulation as well as to provide a circuit for delivery of indicated stimulation pulses. The implantation procedure involves confirmation of the proper placement of the lead(s) as well as the electrical conductivity of the lead circuit(s) and the integrity of the insulation surrounding the conductive elements.
The implantation procedure also includes establishing a variety of electrical characteristics of the circuit between the pulse generator and the cardiac tissue. The electrical characteristics of the circuit(s) between the pulse generator and the heart as well as the characteristics of the heart tissue itself affect sensing of cardiac signals and delivery of electrical stimulation provided by the pulse generator and thus, the signal sensing quality, and the threshold stimulation that must be provided to effectively induce depolarization of the heart. These characteristics include the electrical conductivity of the conductor between the pulse generator and the electrode; the conductivity, surface area, and configuration of the electrode; and the contact between the electrode and the excitable heart tissue.
It is generally desirable to stimulate the heart, when indicated, with a stimulation pulse minimally in excess of a minimum required to effect depolarization. However as effective detection and stimulation are required after implant and, as individual characteristics and requirements vary, many operating parameters of the implantable device relating to arrhythmia detection and stimulation delivery are programmable to provide individually tailored device performance. The determined sensing and stimulation values are used to program operating parameters of the implantable device.
A device often used in the implantation process to test and evaluate the lead integrity, sensing, and stimulation is referred to as a pacing system analyzer (PSA). The PSA is typically only used during an implantation procedure and operates as a pulse generator whose operational parameters are variable. The PSA functions as a surrogate for the implantable device to evaluate the performance of the lead(s) themselves, sensing, and pacing. The characteristics of the sensing and stimulation determined with the aid of the PSA then helps determine the programming of the implantable device.
The initial implantation as well as ongoing clinical care provided to patients with implantable cardiac device systems also generally includes the use of physician programmers. A programmer is a device that enables a clinician to telemetrically communicate with and control an implantable cardiac device such as a pacemaker or ICD. Implantable devices are generally capable of receiving telemetric signals from a programmer to induce the device to set or change a variety of operational parameters of the device related to the therapy provided by the device as well as to select among the physiological parameters that the device monitors and records. As mentioned, these parameters are typically programmed into the device specifically for an individual patient. Data determined following fixation of the lead(s) and with use of a PSA generally is used to determine appropriate programming for the individual patient.
As patient condition can vary over time and improved operating algorithms become available, the parameters are also often desirably changed following the initial implantation to adjust the therapy provided and/or the physiological parameters monitored in order to provide the attending clinician with different information or to adapt the therapy to a more efficacious regimen. It is highly desirable to set these parameters without the expense and health risks to the patient of additional invasive procedures and programmers enable the attending clinician to perform these tasks in a non-invasive, telemetric manner after implantation with the insight of information provided from internal measurements provided by the device itself.
Implantable devices generally monitor and record a variety of internal physiological parameters of the patient and are often provided with a telemetry system to telemetrically transmit those measured and recorded parameters outside the patient's body to a programmer. The implantable devices can also transmit to the programmer data related to present device status, such as programmed operational parameters, battery capacity state, therapy provided and cardiac conditions observed, etc. A clinician can then review the data via the programmer and make any indicated changes in the patient's therapy.
Accordingly, programmers typically include a display to visually present alphanumeric and graphical information relating to device performance and patient condition as well as user input devices to facilitate data entry and control inputs to be provided by a clinician to control device operation telemetrically. As implantable devices are typically battery powered, thus having limited electrical power capacity and, as telemetric communication can be a relatively major source of battery depletion, programmers often include a movable wand with an antenna that is placed on the patient overlying the implanted device to facilitate reception and transmission of signals to/from the implantable device. The wand is placed over the implanted device to be proximate the device to thereby reduce the power required for transceiving and to limit RF interference with or by other nearby devices.
Programmers are particularly useful during the implantation process as the telemetric feedback from the device to the programmer can confirm integrity of the connections of leads to the implantable device after the leads are attached or, conversely, indicate faulty connections thereof. The implantable device can also telemetrically indicate its operational status to the programmer and it will be understood by one of skill in the art that correct device operation is preferably confirmed before closure of surgical incisions.
Both the programmers and PSAs previously described are typically used during an implantation procedure. The combination of these and other medical equipment as well as the number of attending personnel used in a typical implantation procedure can result in a surgery room that is relatively crowded with equipment that is often inconvenient to use due to the crowding and limited space.
From the foregoing, it will be appreciated that there is a need for medical devices offering the functionality of both current PSAs and programmers, but with increased convenience of use. It would be advantageous to provide this functionality while reducing the number of separate pieces of equipment.